JP6532831B2 - Voltage monitoring circuit and voltage monitoring method - Google Patents

Description

  The present embodiment relates to a voltage monitoring circuit and a voltage monitoring method.

  As a power source for electric vehicles, home appliances, etc., there is disclosed a technology of an assembled battery module having a battery cell unit in which a large number of battery cells are connected in series. Further, in the assembled battery module, there is disclosed a technique for detecting the presence or absence of disconnection of a wire from the battery cell unit to the voltage measurement unit.

  In the assembled battery module, in order to remove noise unnecessary for voltage measurement, a filter circuit may be provided in a voltage measurement path from the battery cell unit to the voltage measurement unit. For example, the filter circuit has a capacitance connected between the wirings connecting the positive electrode and the negative electrode of the battery cell to the voltage measurement unit. When leakage occurs in the capacity connected between the wires, a voltage lower than the voltage of the actual battery cell is supplied to the voltage measurement unit. Therefore, whether the drop of the voltage measured by the voltage measuring unit is due to the drop of the voltage of the battery cell or a fault caused in the voltage measurement path due to the leakage of the capacity constituting the filter circuit or the like A technique for voltage monitoring that can be easily detected is desired.

JP, 2015-59762, A

  An object of one embodiment is to provide a voltage monitoring circuit and a voltage monitoring method capable of easily detecting an abnormality in a voltage measurement path from a battery cell unit to a voltage measurement unit.

  According to one embodiment, the voltage monitoring circuit has a first voltage measurement path comprising a first filter circuit comprising a series connection of a first resistor and a first capacitance to which the battery cell voltage is applied. . It has a second voltage measurement path provided with a second filter circuit including a series connection of a second resistor and a second capacitor to which a voltage of the battery cell is applied and which has a resistance value smaller than the first resistor. . A first voltage measurement measuring the voltage of the battery cell via the first voltage measurement path and a second voltage measurement measuring the voltage of the battery cell via the second voltage measurement path It has a voltage measurement unit. It has a comparison circuit to which the measured value of the first voltage measurement and the measured value of the second voltage measurement are supplied.

FIG. 1 is a diagram showing the configuration of the voltage monitoring circuit of the first embodiment. FIG. 2 is a diagram showing an example of a voltage monitoring method. FIG. 3 is a diagram showing the configuration of the voltage monitoring circuit of the second embodiment. FIG. 4 is a diagram showing the configuration of the voltage monitoring circuit of the third embodiment. FIG. 5 is a diagram showing another example of the voltage monitoring method. FIG. 6 is a diagram showing the configuration of the voltage monitoring circuit of the fourth embodiment. FIG. 7 is a diagram showing the configuration of the voltage monitoring circuit of the fifth embodiment. FIG. 8 is a diagram showing another example of the voltage monitoring method. FIG. 9 is a diagram showing the configuration of the voltage monitoring circuit of the sixth embodiment. FIG. 10 is a diagram showing one configuration of the voltage measurement unit.

  Hereinafter, a voltage monitoring circuit and a voltage monitoring method according to an embodiment will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited by these embodiments.

First Embodiment
FIG. 1 is a diagram showing the configuration of the voltage monitoring circuit of the first embodiment. The voltage monitoring circuit of FIG. 1 includes a battery cell unit 10 in which a plurality of battery cells BT1 to BTn are connected in series, and a plurality of voltage measuring units 20-1 to 20-n that measure voltage for each battery cell. Battery cells BT1 to BTn are, for example, secondary batteries such as lithium ion batteries. Each voltage measurement unit 20 includes first and second voltage measurement units 20A and 20B, and is connected between the positive electrode and the negative electrode of the corresponding battery cell.

  Here, connection between the battery cell BT and the voltage measurement unit 20 will be described. Below, 1st battery cell BT1 is demonstrated. The same connection is provided for the other battery cells. The positive electrode of the first battery cell BT1 is connected to the first electrode terminal T1-1. The negative electrode of the first battery cell BT1 is connected to the second electrode terminal T2-1.

  The first positive electrode side wire W1-1 is connected to the first electrode terminal T1-1. The first positive electrode side wiring W1-1 is connected to the first voltage measurement unit 20A-1 via the first resistor R1-1. The first negative electrode side wire WA-1 is connected to the second electrode terminal T2-1. The first negative electrode side wiring WA-1 is connected to the first voltage measurement unit 20A-1 via the resistor RA-1.

  A first capacitance C1-1 is connected between one end of the first resistor R1-1 and one end of the resistor RA-1 on the voltage measurement unit 20-1 side. The first resistor R1-1, the first capacitor C1-1, and the resistor RA-1 constitute a first filter circuit FL-1. When the voltage of the first battery cell BT1 is applied, the first filter circuit FL-1 forms a low pass filter, and the first positive electrode side wire W1-1 and the first negative electrode side wire WA-1 are formed. It functions as a filter that removes noise that is not necessary for voltage measurement that occurs between them. Further, the first positive electrode side wire W1-1 and the first negative electrode side wire WA-1 form a first voltage measurement path for supplying the voltage of the battery cell BT1 to the first voltage measurement unit 20A-1. .

  The second positive electrode side wiring W2-1 is connected to the first electrode terminal T1-1. The second positive electrode side wiring W2-1 is connected to the second voltage measurement unit 20B-1 via the second resistor R2-1. The second negative electrode side wiring WB-1 is connected to the second electrode terminal T2-1. The second negative electrode side wiring WB-1 is connected to the second voltage measurement unit 20B-1 via the resistor RB-1.

  A second capacitance C2-1 is connected between one end of the second resistor R2-1 and one end of the resistor RB-1 on the voltage measurement unit 20-1 side. The second resistor R2-1, the second capacitor C2-1, and the resistor RB-1 constitute a second filter circuit FLA-1. When the voltage of the first battery cell BT1 is applied, the second filter circuit FLA-1 forms a low pass filter, and the second positive electrode side wire W2-1 and the second negative electrode side wire WB-1 are formed. It functions as a filter that removes noise generated between them. Further, the second positive electrode side wiring W2-1 and the second negative electrode side wiring WB-1 constitute a second voltage measurement path for supplying the voltage of the battery cell BT1 to the second voltage measurement unit 20B-1. .

  When an A / D converter that performs sampling operation at a predetermined sampling frequency is used for the first and second voltage measurement units 20A-1 and 20B-1, the first and second filter circuits Fll- 1, It functions as an anti-aliasing filter that removes noise of frequency components exceeding 1/2 of the sampling frequency by setting the cutoff frequency of FLA-1 lower than 1/2 of the sampling frequency of the A / D converter It can be done. As an A / D converter operating at a predetermined sampling frequency, for example, a Δ コ ン A / D converter can be used.

  The cell balance switch SW1 is connected between the second resistor R2-1 and one end of the resistor RB-1 on the voltage measurement unit 20-1 side, that is, in parallel with the second capacitor C2-1. For example, when the battery cell BT1 is overcharged, turning on the cell balance switch SW1 causes a current to flow from the positive electrode side of the battery cell BT1 for discharging, thereby equalizing energy with the other battery cells BT2 to BTn. It can be planned. In order to shorten the discharge time, for example, the resistance value of the second resistor R2-1 is set to a value smaller than the resistance value of the first resistor R1-1. Similarly, for example, the resistance value of the resistor RB-1 is set to a value smaller than the resistance value of the resistor RA-1. The first and second filters are set by setting the resistances R1-1, R2-1, RA-1, and RB-1 and the capacitors C1-1 and C2-1, which are provided in the respective wires, to the same value. The characteristics of the circuits FL-1 and FLA-1, for example, the cutoff frequency may be set to be the same.

  The first voltage measurement unit 20A-1 measures the voltage V1 supplied from the battery cell BT1 via the first voltage measurement path. The second voltage measurement unit 20B-1 measures the voltage V2 supplied from the battery cell BT1 via the second voltage measurement path.

  The measured values of the voltage V1 and the voltage V2 are supplied to the control circuit 40 and to the comparison circuit 30-1. The comparison circuit 30-1 compares the measurement values supplied from the first voltage measurement unit 20A-1 and the second voltage measurement unit 20B-1. Thus, the voltage drop of the battery cell BT1 can be detected. The comparison result by the comparison circuit 30-1 is supplied to the control circuit 40. The control circuit 40 supplies the display unit 50 with the comparison result by the comparison circuit 30-1. The comparison circuit 30-1 calculates the difference between the measurement value of the first voltage measurement unit 20A-1 and the measurement value of the second voltage measurement unit 20B-1, and compares the difference value with a predetermined threshold value. May be configured.

  For example, when the difference between the voltage V1 and the voltage V2 becomes larger than a predetermined threshold value Vth, the control circuit 40 notifies that an abnormality has occurred in the voltage measurement path. For example, when leakage occurs in the first capacitance C1-1, the voltage V1 decreases. When a decrease in voltage V1 is detected, the values of voltage V1 and voltage V2 are compared. Therefore, when the difference becomes larger than the threshold value Vth, for example, it is possible to easily detect that an abnormality has occurred in the voltage measurement path. As the threshold value Vth, for example, a voltage difference between the voltage V1 when there is no leak in the first capacitance C1-1 and the voltage V1 when there is a leak in the first capacitance C1-1 is simulated. And the value of the voltage difference can be used as the threshold value Vth.

  The control circuit 40 can also detect, for example, a state in which the voltage of the voltage cell BT1 is higher than those of the other battery cells BT2 to BTn. When the battery cell BT1 is charged more than the other cells, the control circuit 40 performs control to turn on the cell balance switch SW1, and discharge is performed to perform energy equalization.

  According to the present embodiment, the voltage drop of the battery cell BT occurs in the voltage measurement path by measuring the voltage of the battery cell BT via the first and second voltage measurement paths and comparing the measured values. It is possible to easily detect the phenomenon caused by the abnormality or the phenomenon caused by the voltage drop of the battery cell BT itself by the on-time. Also, by setting the value of the second resistor R2 smaller than the value of the first resistor R1, for example, the cell balance switch SW is turned on, and the battery cell BT with a larger charge amount than the other battery cells is selected. Since the discharge time at the time of discharge can be shortened, equalization of energy balance between the battery cells BT can be achieved in a short time.

  In addition, the voltage measurement paths of each battery cell BT are provided separately from the voltage measurement paths of the other battery cells. For this reason, the voltage measurement of each battery cell BT can be performed while reducing the influence between the voltage measurement paths of the battery cells BT. As a result, for example, setting of the values of the resistors R1, R2, RA, RB and the capacitors C1, C2 provided in the respective voltage measurement paths becomes easy, for example, adjustment of the cutoff frequency etc. can be performed with high accuracy. It can.

  FIG. 2 shows an example of a voltage monitoring method in the voltage monitoring circuit of the first embodiment described above. For example, the voltage V1 of the first battery cell BT1 supplied via the first voltage measurement path and the voltage V2 of the first battery cell BT1 supplied via the second voltage measurement path are measured (S101 ). The difference between the first voltage V1 and the second voltage V2 is compared with a predetermined threshold value Vth (S102). If the difference between the first voltage V1 and the second voltage V2 is larger than the threshold value Vth, it is informed that an abnormality has occurred in the voltage measurement path (S103). For example, a leak is generated in the capacitor C1-1 constituting the first filter circuit FL-1, and the voltage V1 decreases, and it is detected that a voltage difference exceeding the threshold value Vth occurs between the voltage V1 and the voltage V2. I can do it. By monitoring the measurement result of voltage V1 by control circuit 40, when the voltage difference between voltage V1 and voltage V2 does not exceed threshold value Vth, a drop in the voltage of battery cell BT1 itself can be detected. .

Second Embodiment
FIG. 3 is a diagram showing the configuration of the voltage monitoring circuit of the second embodiment. The components corresponding to the first embodiment are assigned the same reference numerals. In the voltage monitoring circuit of the present embodiment, a part of the wiring that constitutes the voltage measurement path of the battery cell BT shown in FIG. 1 is shared. That is, the resistor RA-1 provided on the first negative electrode side wire WA-1 of the first battery cell BT1 to form the first filter circuit FL-1 is the first positive electrode of the second battery cell BT2. It is shared as a part of the side wiring and connected to the first voltage measurement unit 20A-2. The resistor RA-1, the resistor RA-2 provided in the first negative-electrode-side wire WA-2 of the second battery cell BT2, and the capacitance C1-2 connected between these wires form a filter circuit FL- Construct two.

  Further, the resistor RB-1 provided in the second negative electrode side wiring WB-1 of the first battery cell BT1 and configuring the filter FLA-1 is one of the second positive electrode side wirings of the second battery cell BT2. It is shared as a part and connected to the second voltage measurement unit 20B-2 of the voltage measurement unit 20-2. The resistor RB-1, the resistor RB-2 provided on the second negative electrode side wire WB-2 of the second battery cell BT2, and the capacitor C2-2 connected between these wires are connected in the filter circuit FLA-. Construct two. For example, the value of the resistor RB-1 is set to a smaller value than the value of the resistor RA-1.

  In the voltage monitoring circuit of the present embodiment, a part of the wiring that configures the voltage measurement path of each battery cell BT is shared with the wiring of the voltage measurement path of another battery cell. Thereby, the circuit configuration can be simplified. For example, since the resistors RA and RB used to set the cut-off frequencies of the filter circuits FL and FLA are shared, circuit elements can be reduced. When the balance switch SW is turned on also in a configuration in which a part of the wiring of the voltage measurement path is shared among the battery cells BT by setting the value of the resistor RB to a smaller value than the value of the resistor RA. Since the discharge time of the battery cell BT can be shortened, the energy balance among the battery cells BT can be made uniform in a short time.

Third Embodiment
FIG. 4 is a diagram showing the configuration of the voltage monitoring circuit of the third embodiment. The same numerals are given to the composition corresponding to the embodiment as stated above. In the voltage monitoring circuit of the present embodiment, the control circuit 40 supplies a control signal ON / OFF for controlling the operating state of the second voltage measurement unit 20B. The control circuit 40 performs control to stop the supply of the power supply voltage to the second voltage measurement unit 20B, for example, when the operation of the second voltage measurement unit 20B is unnecessary.

  In the normal operation, for example, only the first voltage measurement unit 20A is operated to measure the voltage of the battery cell BT. When the necessity of voltage measurement by the second voltage measurement unit 20B arises as a result of voltage monitoring in the first voltage measurement unit 20A, the control circuit 40 performs control to operate the second voltage measurement unit 20B. . For example, when the voltage V1 drops, the second voltage measurement unit 20B is operated, and measurement is performed by the first voltage measurement units 20A-1 to 20A-n and the second voltage measurement units 20B-1 to 20B-n. It can be configured to compare values.

  According to the present embodiment, power consumption of the voltage monitoring circuit can be reduced by configuring the second voltage measurement unit 20B to operate as needed.

  FIG. 5 shows an example of a voltage monitoring method in the voltage monitoring circuit of the third embodiment. For example, at normal times, the voltage V1 of each battery cell BT supplied via the first voltage measurement path is measured (S201). The voltage V1 is compared with a predetermined threshold value Vth1 to determine whether the voltage V1 is lower than the threshold value Vth1 (S202). If the voltage V1 is not lower than the threshold value Vth1 (S202-No), monitoring is performed only by the first voltage measurement unit 20A. When the voltage V1 becomes lower than the threshold value Vth1 (S202-Yes), the control circuit 40 drives the second voltage measurement unit 20B. In addition to the measurement of the voltage V1, the second voltage V2 is also measured (S203). As the threshold value Vth1, for example, it is possible to set the value of the voltage required to charge the battery cell BT.

  The difference between the measured values of each voltage V1 and voltage V2 is compared with the threshold value Vth (S204). If the difference is larger than the threshold value Vth (S204-Yes), it is notified that an abnormality has occurred in the voltage measurement path (S205). When the difference is equal to or less than the predetermined threshold value Vth (S204-No), it is notified that the voltage of the battery cell BT that has become equal to or less than the threshold value Vth has decreased (S206). The second voltage measurement unit 20B drives only the second voltage measurement unit 20B that measures the voltage of the battery cell whose voltage V1 is lower than the threshold value Vth based on the voltage V1 of each battery cell, for example. Good. This further reduces the power consumption of the voltage monitoring circuit.

  According to the voltage monitoring method of the present embodiment, for example, when the voltage of the battery cell BT is higher than the threshold value Vth1, the power consumption of the voltage monitoring circuit can be achieved by operating only the first voltage measuring unit 20A. Can be reduced. When the voltage V1 drops below the threshold value Vth1, the second voltage measurement unit 20B is operated to compare the measured values of both the voltages V1 and V2 supplied from the first and second voltage measurement paths. Thus, it can be easily detected whether the detected voltage drop is due to an abnormality occurring in the voltage measurement path or due to the voltage drop of the battery cell BT itself.

Fourth Embodiment
FIG. 6 is a diagram showing the configuration of the voltage monitoring circuit of the fourth embodiment. The voltage monitoring circuit of the third embodiment shown in FIG. 4 is configured to share a part of the wiring that constitutes the voltage measurement path of the voltage V1 and the voltage V2 as in the second embodiment. The components corresponding to the embodiment of FIG. 4 are denoted by the same reference numerals. In the voltage monitoring circuit of this embodiment, for example, a resistor connected to a voltage measurement path and used to set the cutoff frequency of the filter circuit (FL-1 to FL-n, FLA-1 to FLA-n) Since (RA-1 to RA-n and RB-1 to RB-n) are shared, circuit elements can be reduced. In addition, the power consumption of the voltage monitoring circuit can be reduced by operating the second voltage measurement unit 20B as necessary when the voltage V1 is lower than the threshold value Vth or the like by the control circuit 40. .

Fifth Embodiment
FIG. 7 is a diagram showing the configuration of the voltage monitoring circuit of the fifth embodiment. The same numerals are given to the composition corresponding to the embodiment as stated above. The voltage monitoring circuit of the present embodiment has a selection circuit 70 which selects one of the first voltage measurement path and the second voltage measurement path of each of the battery cells BT1 to BTn and supplies the selected voltage measurement portion 200.

  The selection circuit 70 has switching terminals MT1, MT2, MTA, MTB, and switches MPSWA, MPSWB for each battery cell. The selection circuit 70 controls the switches MPSWA and MPSWB by the control circuit 40 to switch the voltage measurement path. Hereinafter, battery cell BT1 will be described. The same applies to the other battery cells. The switching terminal MT1-1 is connected to the first electrode terminal T1-1 via the resistor R1-1. The switching terminal MT2-1 is connected to the first electrode terminal T1-1 via the resistor R2-1. The switching terminal MTA-1 is connected to the second electrode terminal T2-1 via the resistor RA-1. The switching terminal MTB-1 is connected to the second electrode terminal T2-1 via the resistor RB-1. The first voltage measurement path is formed by connecting the switch MPSWA-1 to the switching terminal MT1-1 and connecting the switch MPSWB-1 to the switching terminal MT2-1. Similarly, the second voltage measurement path is formed by connecting the switch MPSWA-1 to the switching terminal MT2-1 side and connecting the switch MPSWB-1 to the switching terminal MTB-1 side.

  The voltage measurement path connected to each battery cell BT is switched by the switches MPSWA and MPSWB, and the voltage of each battery cell BT is measured by the voltage measurement unit 200. A storage circuit unit 250 is connected to the voltage measurement unit 200. The memory circuit portion 250 includes a first memory circuit 251 and a second memory circuit 252. The first memory circuit 251 holds, for example, the measured value of the first voltage V1 in the first voltage measurement path, and the second memory circuit 252 generates the second voltage V2 in the second voltage measurement path. Hold the measured value.

  The comparison circuit 300 compares the measured value held in the first memory circuit 251 with the measured value held in the second memory circuit 252. The output of the comparison circuit 300 is supplied to the control circuit 40. The comparator circuit 300 calculates the difference between the measured value held in the first memory circuit 251 and the measured value held in the second memory circuit 252, and compares the difference value with a predetermined threshold value. It may be

  The voltage monitoring circuit of the present embodiment has a selection circuit 70 which selects the voltage measurement path of each battery cell BT and supplies it to the voltage measurement unit 200. Therefore, the voltage measurement path of each battery cell BT can be selected by the selection circuit 70 and can be measured by the common voltage measurement unit 200. Since the voltage of each battery cell BT can be measured by the common voltage measurement unit 200, the number of circuit elements in the voltage measurement unit is reduced, and the circuit configuration is simplified. When the number of battery cells BT to be measured increases, the effect of reducing the number of circuit elements by sharing the voltage measurement unit increases.

  FIG. 8 shows an example of a voltage monitoring method in the voltage monitoring circuit of the fifth embodiment. For example, the voltage V1 of the battery cell BT is measured using the first voltage measurement path (S301). The first voltage V1 is compared with the threshold value Vth (S302). If the first voltage V1 is not lower than the threshold value Vth (S302-No), the measurement of the first voltage V1 is continued (S301). If the first voltage V1 is lower than the threshold Vth (S302-Yes), the measured value of the first voltage V1 is stored (S303). Subsequently, the voltage V2 is measured using the second voltage measurement path (S304). The connection destinations of the switches MPSWA and MPSWB are switched to switch the voltage supplied to the voltage measurement unit 200 from the first voltage V1 to the second voltage V2. The measured value of the second voltage V2 is stored (S305). The measured values of the first voltage V1 and the second voltage V2 are held, for example, in the first memory circuit 251 and the second memory circuit 252, respectively.

  The first voltage V1 and the second voltage V2 are compared (S306). If the difference between the measured values of the first voltage V1 and the second voltage V2 is larger than the threshold Vth (S306-Yes), it is notified that an abnormality has occurred in the corresponding voltage measurement path (S307). If the difference between the measured values of the first voltage V1 and the second voltage V2 is less than or equal to the threshold value Vth (S306-No), it is notified that the voltage of the corresponding battery cell BT has decreased (S308).

  According to the voltage monitoring method of the present embodiment, when the voltage V1 supplied via the first voltage measurement path falls below the threshold value Vth1, the voltage is switched to the second voltage measurement path and the voltage V2 is measured. The difference between the measured values is compared with the threshold value Vth to detect whether or not the voltage drop occurs due to an abnormality in the voltage measurement path. By switching the voltage measurement path, the voltage of each of the battery cells BT1 to BTn can be measured by the common voltage measurement unit 200, so that the circuit configuration can be simplified. The state of the voltage of each of the battery cells BT1 to BTn connected in series can be monitored in time division by sequentially selecting the battery cells BT to be measured by the selection circuit 70 at predetermined timing.

Sixth Embodiment
FIG. 9 is a diagram showing the configuration of the voltage monitoring circuit of the sixth embodiment. The same numerals are given to the composition corresponding to the embodiment as stated above. In the voltage monitoring circuit of the present embodiment, the wiring forming the voltage measurement path of the battery cell BT of the embodiment shown in FIG. 7 is shared. That is, the first negative-electrode-side wiring WA-1 of the first battery cell BT1 is shared as the first positive-electrode-side wiring of the second battery cell BT2 and is connected to the switching terminal MT2-1. Further, the second negative electrode side wiring WB-1 of the first battery cell BT1 is shared as a second positive electrode side wiring of the second battery cell BT2 and is connected to the switching terminal MTB-1.

  By selecting the switching terminals MTA-1 and MTA-2, the resistor RA-1, the resistor RA-2, and the capacitor C1-2 connected between these wires form a filter circuit FL-2. By selecting the switching terminals MTB-1 and MTB-2, the resistor RB-1, the resistor RB-2, and the capacitor C2-2 connected between these lines constitute the filter circuit FLA-2. .

  The selection circuit 70 has connection terminals in addition to the switching terminals MT1, MT2, MTA, and MTB. The connection terminal is an input terminal on the voltage measurement unit 200 side of the switch MTSWB. One end of the switch MTSWB is connected to the first switching terminal MTA or the second switching terminal MTB, and the other is connected to the first connection terminals MT2-1A to MT2-nA or the second connection terminals MT2-1B to MT2-nB. Connect to That is, the switch MTSWB includes switching units MTSWB-1A to MTSWB-nA on the battery cell BT side and switching units MTSWB-1B to MTSWB-nB on the voltage measurement unit 200 side.

  The switch MTSWA-1 is connected to the switching terminal MT1-1, and the switch MTSWB-1 is connected to the switching terminal MTA-1 and the connection terminal MT2-1B. Thereby, a first voltage measurement path is formed, and the voltage V1 of the battery cell BT1 is supplied to the voltage measurement unit 200. Further, the switch MTSWA-1 is connected to the switching terminal MT2-1, and the switch MTSWB-1 is connected to the switching terminal MTB-1 and the connection terminal MT2-1B. Thereby, a second voltage measurement path is formed, and the voltage V2 of the battery cell BT1 is supplied to the voltage measurement unit 200.

  Similarly, the switches MTSWA and MTSWB of the selection circuit 70 are selected to switch the switching terminals MTA and MTB on the battery cell BT side, and the connection terminals MT2-1A to MT2-nA and MT2-1B on the voltage measurement unit 200 side. Switch MT2-nB. Thus, different voltage measurement paths can be formed, and the voltage of each of the battery cells BT1 to BTn can be measured by the voltage measurement unit 200.

  In the voltage monitoring circuit of the present embodiment, the wires WA and WB that constitute the voltage measurement path of each battery cell BT are shared as the wires of the voltage measurement paths of the other battery cells. For example, since the resistors RA and RB used to set the cutoff frequencies of the filter circuits FL and FLA are shared, circuit elements can be reduced.

  FIG. 10 is a diagram showing one configuration of the voltage measurement unit 200. As shown in FIG. The voltage measurement unit 200 is configured by a ΔΣ A / D converter that digitizes an analog signal using ΔΣ modulation. Specifically, the voltage measurement unit 200 has a ΔΣ A / D modulator 210 and a decimation filter 220. An analog input signal Vin is supplied to the ΔΣ A / D modulator 210. For example, the voltage of each battery cell BT is supplied. The ΔΣ A / D modulator 210 is, for example, a Δ circuit (not shown) for obtaining a difference between the input signal Vin and a certain fixed voltage, a 回路 circuit (not shown) for sequentially adding the operation results of the Δ circuit, a predetermined sampling A quantization circuit (not shown) which compares the operation result of the Σ circuit with a certain value by frequency and quantizes it, and a switch circuit (not shown) which operates according to the output of the quantization circuit .

  The decimation filter 220 performs band limiting and decimation on the output of the ΔΣ A / D modulator 210. The output signal of the decimation filter 220 is output as a digital output.

  By using the configuration of the ΔΣ A / D converter provided with the decimation filter 220 having the function of a digital filter as the voltage measurement unit 200, it is possible to perform voltage measurement that is less susceptible to noise. Therefore, for example, the characteristics of the first filter circuit FL and the second filter circuit FLA are different, and even when the cutoff frequencies do not match completely, the influence of noise when measuring the voltage of each battery cell BT is mitigated. I can do it. In this way, it is possible to provide a margin in setting the values of the resistance and the capacitance that make up the first filter circuit FL. Therefore, by using the configuration of the ΔΣ A / D converter, the second resistance R2 connected to the cell balance switch SW is made smaller than the first resistance R1 to shorten the energy balance among the battery cells BT. It will be easier to maintain in time. In addition to the ΔΣ A / D converter, it is possible to add a digital filter circuit to the A / D converter which performs sampling at a predetermined frequency as the voltage measurement unit 200.

  While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

  Reference Signs List 10 battery cell unit, 20-1 to 20-n voltage measurement unit, 30-1 to 30-n comparison circuit, 40 control circuit, 50 display unit, 60 switch unit, 70 selection circuit, 200 voltage measurement unit, 250 memory circuit Part, 300 comparison circuits.

Claims (6)

A first voltage measurement path comprising a first filter circuit including a series connection of a first resistor and a first capacitance to which a first voltage of the battery cell is applied;
A second voltage measurement path comprising a second filter circuit to which a second voltage of the battery cell is applied and which includes a series connection of a second resistor and a second capacitor having a smaller resistance value than the first resistor When,
A voltage measurement unit that measures the first voltage via the first voltage measurement path and measures the second voltage via the second voltage measurement path;
A comparison circuit that compares a difference between the measured value of the first voltage and the measured value of the second voltage with a predetermined first threshold value ;
A voltage monitoring circuit comprising:   The voltage measurement unit is an A / D converter having a ΔΣ A / D modulator performing sampling operation at a predetermined sampling frequency, and a digital filter circuit performing band limitation and decimation processing on the output of the ΔΣ A / D modulator. The voltage monitoring circuit according to claim 1, further comprising: A selection circuit that selects any one of the first voltage measurement path and the second voltage measurement path and supplies the first or second voltage to the voltage measurement unit ;
The second voltage measurement path is selected to measure the second voltage when the first voltage measured via the first voltage measurement path falls below a predetermined second threshold. Control circuitry to control the selection circuitry to supply to the
The voltage monitoring circuit according to claim 1, comprising: A first voltage measurement path comprising a first filter circuit including a series connection of a first resistance and a first capacitance to which a battery cell voltage is applied;
A second voltage measurement path comprising a second filter circuit including a series connection of a second resistor and a second capacitor to which the battery cell voltage is applied;
A first voltage measurement of the voltage of the battery cell via the first voltage measurement path, and an voltage of the battery cell via the second voltage measurement path, comprising an A / D converter having a digital filter function A voltage measurement unit for performing the second voltage measurement of
A measurement value of the first voltage measurement and a measurement value of the second voltage measurement are supplied , and a difference between the measurement value of the first voltage measurement and the measurement value of the second voltage measurement and a predetermined threshold value are provided. a comparison circuit that compares,
A voltage monitoring circuit comprising: Measuring a first voltage of the battery cell via a first voltage measurement path having a first low pass filter circuit,
Measuring a second voltage of the battery cell via a second voltage measurement path having a second low pass filter circuit,
Comparing the difference between the value of the first voltage and the value of the second voltage with a predetermined first threshold value ,
Informing that an abnormality has occurred in the first voltage measurement path or the second voltage measurement path when the difference between the first voltage and the second voltage is larger than the first threshold. A method of monitoring voltage characterized by If the value of the first voltage measured via the first voltage measurement path changes beyond a predetermined second threshold, the second voltage is measured via the second voltage measurement path. The voltage monitoring method according to claim 5, wherein the voltage monitoring is performed.

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